Production of artificial materials from cellulose derivatives



Patented Apr. 4, 1933 UNITED STATES PATENT OFFICE ROBERT PIERCE ROBERTS, REGINALD IVOR REID DEAN, AND LOUIS WILFRED GREGORY,

OF SPONDON, NEAR DERBY, ENGLAND, ASSIGNORS TO CELANESE CORPORATION AMERICA, A CORPORATION OF DELAWARE PRODUCTION or ARTIFICIAL MATERIALS FROM cELLULosE DERIVATIVES No Drawing. Application filed February 27, 1930, Serial No. 431,966, and in Great Britain May 9, 1929.

- This invention relates to the production of artificial filament, threads, ribbons, films and the like by-wet-spinning processes from solutions containing cellulose derivatives, for example cellulose acetate, formate, propionate, butyrate or other carboxylic acid esters or other esters of cellulose, or methyl, ethyl or benzyl cellulose or other cellulose ethers.

According to the present invention filamerits, threads, ribbons, films and the like of good strength may be obtained by extruding solutions of cellulose derivatives into relatively strong mineral acids or acid esters thereof, for example aqueous solutions of sulphuric acid, hydrocholoric acid or phosphoric acid or of ethyl sulphuric acid, mono or di-ethyl phosphoric acid and the like. We find that good spinning may be obtained with relatively strong mineral acids or mineral acid esters and particularly with sulphuric acid solutions, provided that the strength of the solutions be adjusted to avoid a deleterious or undesired degree of hydrolysis of the cellulose ester or ether.

According to a modification of the invention the solutions containing the cellulose derivatives may be extruded into any suitable precipitating bath and thereafter carried into a bath containing relatively strong min-eralacid or acid ester thereof.

The filaments or other products thus obtained or thus treated may be, and preferably are, given an air-run after the treatment with the mineral acid or acid ester. After the air-run, in order to avoid destruction of the products consequent upon prolonged contact with the acidic substances, the materials may be freed therefrom, for example by washing with water alone or with water containing alkali or base. As indicated above the concentration of the baths, either. precipitating bath or subsequent treatment bath, should be adjusted to avoid a deleterious .degree of hydrolysis of the cellulose ester or ether. It is also found that for each acid or acid ester there exists a range of concentration within which stable spinning may be obtained. As the concentration of the mineral acid, and particularly sulphuric acid, in the precipitating bath or subsequent treatment bath is increased or as the time of immersion in the bath is increased, the products tend to become, progressively dull and may, if the concentration be carried sulficiently high or the time of immersion increased sufliciently, become straw-like to the touch. This latter possibility is of advantage in the production of ribbons where it is frequently desirable that the products should have this property. WVhile the stability of spinning and the hydrolysis of the cellulose ester or ether is dependent upon the concentration used, it is also dependent upon the speed of spinning and upon the time of immersion in the bath, so that with higher speeds of spinning or with shorter lengths of immersion, the concentration in the bath may be increased. It is preferable to use sufficiently high acid concentrations to avoid the production of precipitated opaque products. For example in order to obtain clear products concentrations of sulphuric acid below 20% should be avoided.

In order to moderate or to render more uniform the action of the mineral acid, additions, for example of glycerine, glucose or other sugars, alcohols or sulphonated oils, may be made to the baths. Furthermore, if

desired, in order to increase the stability of spinning, solvents or latent solvents may be added to the baths as described in U. S. Patent Specification No. 1,467,493. Similar additions may, if desired, be made to acid ester baths. Such solvents or additions preferably have no action on the mineral acids or acid esters.

The filaments, yarns or ribbons may be spun under tension according to the present invention, or if the mineral acid or acid ester be contained in a subsequent treatment bath, such treatment may take place under tension or not, or alternatively the products after production or treatment may be stretched or may be dried under tension.

The following examples illustrate the invention but are not to be considered as limiting it in anyway i Example 1 i 4 A 20% acetone solution of cellulose acetate is spun at a speed of 20 metres per minute into a bath consisting of 32% aqueous sulphuric acid, the length of immersion being about 6 inches. On emerging from the bath the yarn is passed over a feed roller and thence into a bath containing dilute ammonia, after which it may be wound, for example on bobbins, or may be twisted or hanked. The hanks may be washed and dried under a slight tension. Yarns or threads consisting of filaments of good lustre, strength and appearance are thus obtained.

E mamp le 2 A 20% acetone solution of cellulose acetate is spun into a bath containing 40% aqueous sulphuric acid, the speed of spinning and the length of immersion being the same as in Example 1.

E trample 3 Filaments are spun as in Example 1, but using a precipitating bath consisting of 46% aqueous sulphuric acid. The filaments obtained are much duller than those obtained in Example 1.

E wample 4 A 30% acetone solution of cellulose acetate is spun at a rate of 3 metres per minute through jet orifices suitable for obtaining ribbons and having a width of about .07 millimetres, into a precipitating bath consisting of a 30% aqueous solution of sulphuric acid, the length of immersion being about 3 feet. The ribbon on leaving the acid bath is passed into a bath containing dilute ammonia and is then reeled whilst running in water. A clear strong straw-like ribbon is thus obtained.

E wample 5 A 25% acetone solution of cellulose acetate is spun at a speed of 25 metres per minute into a bath consisting of a aqueous solution of diacetone alcohol. On emerging from the bath the yarn is passed into a second bath consisting of a 32% aqueous solution of sulphuric acid. the length of immersion being about 6 inches. On emergence from this bath the yarn is thereafter treated as in Example 1.

In a similar manner products may be obtained by spinning into aqueous solutions of hydrochloric acid or phosphoric acid or other mineral acids or partially esterified polybasic mineral acids. The strength of the baths to be used for any given length of immersion and any given speed may be readily ascertained by experiment.

hat we claim and desire to secure by Letters Patent is 1. Process for the manufacture of artificial materials by wet spinning processes from solutions of cellulose derivatives in organic solvents, comprising subjecting the materials continuously With their production to the action of a strong solution of a substance selected from the group consisting of strong mineral acids and acid esters of strong mineral acids.

2. Process for the production of artificial materials by Wet spinning processes from solutions of cellulose derivatives in organic solvents, comprising extruding the solutions into a bath containmg a strong solution of a substance selected from the group consisting of mineral acids and acid esters of strong mineral acids.

3. Process for the production of artificial materials by wet spinning processes from solutions of cellulose acetate in organic solvents, comprising extruding the solutions into a bath containing a strong solution of a substance selected from the group consisting of mineral acids and acid esters of strong mineral acids.

4. Process for the manufacture of artificial materials by Wet spinning processes from solutions of cellulose derivatives in organic solvents, comprising subjecting the materials continuously with their production to the action of strong aqueous sulphuric acid.

5. Process for the manufacture of artificial materials by Wet spinning processes from solutions of cellulose derivatives in organic solvents, characterized in that the materials are extruded into a coagulating medium and thereafter treated with a strong solution of a substance selected from the group consisting of a strong mineral acid and acid esters of strong mineral acids.

6. Process for the manufacture of artificial materials by wet spinning processes from solutions of cellulose acetate in organic solvents, characterized in that the materials are extruded into a coagulating medium and thereafter treated With a strong solution of a substance selected from the group consisting of a strong mineral acid and acid esters of strong mineral acids.

7. Process for the manufacture of artificial materials by Wet spinning processes from solutions of cellulose derivatives in organic solvents, comprising subjecting the materials continuously with their production to the action of a strong solution of a substance selected from the group consisting of strong mineral acids and acid esters of strong mineral acids, and thereafter washing the materials.

ln testimony whereof we have hereunto subscribed our names.

ROBERT PIERCE ROBERTS. REGINALD IVOR REID DEAN. LOUIS XVILFRED GREGORY. 

